Thermal floor covering



Nav. 20, 1956 M. D. LlcH'n-:NsTElN l 2,771,537

THERMAL FLOOR COVERING Filed June 4, 1954.

` E Ils/VENTOR 36 l maoim United States Patent O THERMAL FLOOR COVERING Morris D. Lichtenstein, Chicago, Ill.

Application June 4, 1954, Serial No. 434,469

2 Claims. (Cl. 219-46) This invention relates to a oor covering and more particularly to an improved oor covering incorporating a source of heat therein.

It is a principal object of this invention to provide an improved method and apparatus for room heating. Certain problems have been universally recognized in the heating and Ventilating industry, some of which are of long standing, others having originated with modern architecture and home planning. The effect of convection forces on the air within a room or other enclosed space concentrates the warm air in the upper regions of the room, whiie the floor area may be substantially below a comfortable living temperature. This has been recognized as a basic physical phenomenon and has been coped with in part by the positioning of hot air vents or radiators as close to the oor as possible. In addition to this ever present problem, modern architecture is, in many instances, providing living quarters constructed on footings which maintain the floor level only a short distance above the ground. As the ground will generally be relatively cold and damp, this produces additional undesired loss of heat through the floor areas of such liv'- ing quarters. Other home constructions now utilize a single concrete slab poured directly onto the ground, in which event the slab will generally be cold and damp unless expensive precautions are taken to prevent this condition. One method which has been proposed for maintaining the oor area at a more desirable temperature is the inclusion of heating coils within such a concrete slab and passing hot water or steam through said coils. Such panel heating overcomes the detrimental effects of convection at least in part, but clearly cannot be installed in any existing structures without great expense and is not satisfactory in many new structures.

It is, therefore, a further object of this invention to provide an improved system of room heating which may be either independent of existing facilities or combinedl therewith as an integrated unit.

It is another object of this invention to provide an improved oor mounted heating unit which is readily susceptible to repair, maintenance or replacement.

It is still another object of this invention to provide a oor covering incorporating a heating unit therein which can be cleaned, removed or stored conveniently when desired.

lt is another object of this invention to provide an improved floor covering which incorporates a source of thermal energy as well as insulates against the loss of heat through the adjacent floor area.

It is another object of this invention to provide an im? heat during marginal periods when small quantities of heat are required.

It is another object of this invention to provide an improved oor covering and heat source whereby rooms may be individually varied in temperature from a predetermined ambient level, said ambient level being dictated by the central heating system.

Further land additional objects of this invention will become manifest from a consideration of this specification, the accompanying drawing and the appended claims.

In one form of this invention a conventional pile fabric rug is provided in conjunction with an electric heating element and a foam rubber base. More particularly an electric heating element having two separate conductors capable of providing various degrees of heat is permanently secured between a sponge rubber base and a pile fabric covering with the base fused into the interstices of the fabric.

For a more complete understanding of this invention reference will now be made to the accompanying drawing wherein:

Fig. 1 is a diagrammatic plan View of one embodiment of this invention shown partially in section;

Fig. 2 is a vertical sectional view taken on the line 2-2 of Fig. l;

Fig. 3 is a group of electrical schematic diagrams indicating the manner in which various degrees of heat are available from the embodiment of Fig. l;

Fig. 4 is a diagrammatic view partially in section of the switch of the embodiment shown in Fig. 1; and

Fig. 5 is a partial View of portions of the switch shown in Fig. 4, illustrating the relative positions of the various contacts on the wafers thereof.

Referring now to the drawings and more particularly to Figs. 1 and 2, a rug covering 10 is provided which is of laminated construction having a sponge rubber base 12 fused to a pile fabric 14 with spaced electrical conductors 16 and 18 which comprise the heating element 19 disposed therebetween. As shown herein the conductors 16 and 18 are enclosed within a sheath 20 composed of a material such as asbestos which is capable of withstanding relatively high temperatures, `although it is contemplated that such a sheath could be omitted as the normal operating temperature of this heating unit will be below a hazardous level. The heating element has two independent heating circuits which terminate in a switch and plug unit 34. The conductors 16 and 18 are connected together at one end 22 and have a rst length 24 which extends along one edge of the oor covering 10 and then doubles back sucessively over the first course 24 with successive lengths 26 in spaced relationship. A knee 28 is formed at each end of the individual length 26 whereby the lengths 26 are all connected seriatim. A transverse heating element length 30 is connected to the free end of the last course 32 of the parallel lengths 26 to form two complete circuits for passing heating current therethrough.

The return length 3l? having two independent conduc- 'tors and the lead-in conductor 22. are `connected into the plug and switch unit 34. The switch unit 34 has a conventional pair of prongs 36 adapted Afor insertion into a conventional socket which is connected to a commercial source of power. Customarily such a power sourceV will be a 11G volt. 60 cycle supply. Such a source should be capable of delivering power in the order of 1500 watts without overloading the associated circuit protection equipment. A knob 33 vis rotatably mounted on the. socket 34 and rotation thereof effects switching of the contacts contained within the socket 34 to provide various degrees of heat as desired. The exact nature of the switch ing will be explained in detail hereinafter.

The pile fabric may be formed in any conventional manner, but as here `shown and described comprises a plurality of threads 40 which lie in parallel spaced relationship to form a warp and a plurality of interwoven 'threads 42 which constitute a weft. The pile or nap 44 may be secured to the warp in any conventional manner either by knotting or rnerely by frictional engagement between the adjacent threads of the warp and weft. After the complete formation of the laminated unit, the pile is trimmed to form a carpet having a smooth upper surfalce. In manufacture the complete pile fabric is initially formed after which the grid of electrical heating element is placed thereon generally with the fabric in an inverted position. The conductors may be attached to the fabric by stitching, if so desired, or may merely rest upon the fabric 'to be secured thereto by the application of the sponge rubber base l2. The base l2 may be applied 'in any one of a plurality of well-known manners, the most common of which include the spraying of aerated liquid latex whereby the latex is deposited upon the fabric portion of the carpet i4 and is thereafter cured to rigidly engage the interstices `of said fabric. In the alternative an aggregate of liquid latex and an appropriate gas such as air may initially be formed in a hopper and deposited upon the fabric base of the rug 'i4 while said rug is passing under the hopper in an inverted position. After the initial deposition of sponge rubber the entire laminated construction is cured, the exact time and temperature of curing depending upon the material used `and the thickness of the deposit. Generally a curing `time ofthe order of tive to twenty minutes is required.

The sponge rubber base i2 in addition to supporting the heating element against the rug 14 serves to insulate the element from the floor upon which the carpet rests. Thus, though the iioor may be of concrete construction or be exposed to the cold 'areas under a living quarters, the heat generated in the resistance heating element will not be dissipated downwardly `but will warm the pile fabric thei'eabove, providing a substantial area of contact with the air in the room whereby substantial heat transfer to said air is effected. The air so heated will rise due to convection, thus producing increased warmth in the entire room and especially in the oor area. Because of the large heating area provided, t-he temperature differential between the heating element land the surrounding air may be small. It is contemplated that the lengths of heating element be placed approximately 4 inches apart in one embodiment of the invention; thus `for a 9 x l2 rug, the length of heating element is somewhat less than 350 feet. The individual conductor lengths are shown with a flat lcross section in the transverse sectional view of Fig. 2. While this is 'believed advantageous, round conductors may be employed `satisfactorily. In one typical embodiment, a material was used having substantial ductility, a high resistivity, and a high temperature coelicient of resistance. The latter property is desirable in that is provides a 'degree of thermal regulation where, for any reason, a section or all of the rfloor area begins to heat excessively. The cross sectional area `of the conductors 16 and 18 will depend upon the total resistance required, which is, in turn, a function of the heat desired. In one particular oase, four heat levels were required providing energy dissipation at the rate of 1300, 800, 500 and 300 watts respectively.

As shown in Fig. 3, the described embodiment of the invention provides four possible combinations of heating conductors to produce vfour degrees of heat. The two resistance elements '16 and 18 will normally be of different resistance values whereby the use of either one of the elements independently will produce one predetermined heat level. For example, in a unit designed for 120 volt operation the heating element 16 may be selected to have a resistance of the order of 18 ohms such that 800 Watts will be dissipated therein when the resistance is energized. The second heating element may be selected to dissipate energy at the rate of 500 watts, for example, in which event the resistance off element 18 is in the order of 26 ohms. If vthe contacts forming a part of switch and socket unit 34 are positioned as shown in circuit diagram 46 of Fig. 3, the elements 16 and 18 are connected in series from line terminal 48 through contact 70 to the -terminal 82 connected to the free end S3 of conductor 16, `the two resistance wires I6 and 1'8, a conductor 85 connected to the free end of heater 18, terminal 92, and contact 72 to line terminal 50. This circuit presents a resistance of approximately 44 ohms, producing heat dissipation at the rate of about 300 watts. If the switch contacts 70 and 72 are shifted to the position shown in circuit diagram 52 of Fig. 3, heating element 18 is energized alone whereby energy is dissipated at the rate of approximately 500 watts. The heating circuit is completed from line terminal 4S through contact 70, terminal 96, heater 18, terminal 92 and contact 72 to line terminal 50. Upon rotating knob 38 to the fourth position, the contacts '70 and '72 are positioned as `shown in circuit diagram 54 of Fig. 3 in which only heating element 16 is connected to the source of power whereby approximately 800 watts is dissipated. The circuit `is from line terminal 48 through contact 70, `terminal 82, heater 16, terminal 92 and contact 72 to line terminal S0. Circuit diagram 56 illustrates the configuration when the knob is rotated to the lifth position, highest degree of heat available. In this position contact 72 engages the common terminal of the heating elements 16 and 18, while contact 70 engages each of the otherwise free terminals of heating elements 16 and i3, thus placing the heating elements in parallel and providing la total heat dissipation of about 1300 watts.

While the switching for various degrees of heat as herein described may be accomplished by any one of a plurality of familiar devices, one particular device is herein described which is especially well adapted for use with a heated rug or carpet as it is simple in construction, will not consume any substantial space, and is integrally formed with the plug which will normally be in engagement with the wall socket. The knob 38 is iixed to a shaft 62 rotatably mounted in the switch housing 35, said shaft having contact wafers 53 and 60 as well as a spring clip 64 iixed thereto. The spring clip 64 serves as a detent to maintain the desired position of the switch contacts. The spring detent 64 has a small aperture therein which receives a lloating ball 66 engageable with a plurality of depressions 68 formed in the switch housing 34. This assembly determines a plurality of positions which the knob 38 may assume. In this embodiment the positions available are tive in number, the first being an off position in which neither heating element is energized and the other four being positions of increasing heat as explained with respect to Fig. 3.

As shown in Fig. 5 the wafers 58 and 60 have been positioned in side by side relationship to illustrate the manner in which the various circuits are energized. It will be clear that these wafers are normally mounted in tandem. Each of the wafers is composed of an electrically insulated material such as a phenolic resin and shaped metal plates 70 and 72 are secured to the wafers 58 and 60, said plates having desired coded radial extensions or tabs for completing the various circuits as described with respect to Fig. 3. Various contacts are secured in the housing 35 and are adapted to engage alternately the wafers 58 and 60 or the metal plates 70 and 72 which are secured thereto. Referring specitically to the contact configuration with respect to wafer 58 a spring contact 74 is secured in the housing 34 and engages resiliently a complete annular central portion 76 of the metal plate 70. This spring contact is continuously connected to one of the plug prongs 36 comprising line terminal 48 whereby insertion of the prongs into an appropriate socket connects the metal plate 70 to one side of the commercial line. As shown in Fig. 5, the plate 70 is isolated from any other electrical circuit but it will be clear that if the wafer 58 is rotated in a clockwise direction the tab 78 extending outwardly from the annular portion 76 of the plate 70 will engage a contact 80 which is mounted in the housing 34 and is in resilient engagement with the wafer 58. This will apply the incoming line voltage to terminal 82 which corresponds to one of the three terminals of the heating elements as described with respect to Fig. 3.

The second wafer 60 is also shown in its initial position with a spring contact 84 in engagement with the central annular portion 86 of the plate 72, the contact 84 being connected to terminal 50, the other of the two prongs 36 which engage the commercial supply. As illustrated, the conducting plate 72 is isolated from any other circuit whereby the heating element is not energized when the switch is in the position shown. If the wafer 60 is rotated in a clockwise direction along with the wafer 58, said wafers being keyed to the common shaft 62, spring contact 88 mounted in the housing 34 engages the tab 90 extending radially outwardly from the annular portion 76 of plate 72. Thus, a circuit is completed from the incoming line to terminal 92 completing the series circuit as shown in diagram 46 of Fig. 3 and traced with respect thereto. If the shaft 62 is shifted to the next position clockwise tab 78 engages resilient contact 94 and tab 90 remains in engagement with contact 98. Thus a circuit is completed between terminals 92 and 96 corresponding to the situation illustrated by diagram 52 of Fig. 3 in which only heater 18 is energized. If the shaft 62 is again shifted one clockwise position, tab 78 engages contact 98 and a second tab 100 extending radially from plate 72 engages resilient contact 102. Thus a circuit is completed between terminals 82 and 92 as illustrated in diagram 54 of Fig. 3 energizing only heater 16. If the shaft 62 is shifted to its fifth and last position the tab 78 engages contact 104 and a second tab 106 engages contact 108 placing terminals 82 and 92 in a common circuit with the incoming line. At the same time tab 100 remains in engagement with contact 102 placing the two heating elements in parallel and completing the circuit as illustrated in diagram 56 of Fig. 3. A system of stops is provided on wafer 60 to limit the rotation of the shaft 62. Stops 104 and 106 are fixed in housing 35 and engageable by stop 108 which is a radial extension of wafer 60. Thus a device is herein shown and described utilizing two heating elements uniformly disposed in a floor covering having a sponge rubber base and integrally formed pile fabric in which four degrees of heat are provided with a relatively simple switch construction. All of the diagrams and figures of the drawing are schematic in nature for the purposes of better illustrating the principles involved, and it is believed clear that one skilled in the art may conceive various combinations of fabric, base, and heating elements that will serve particular purposes, while conforming to the basic teaching of this invention.

For example, a more elaborate control may be employed whereby the temperature may be continuously varied throughout a substantial range. Also various carpet and rug constructions may be employed for use in various rooms and under any condition. For example,

a carpet of cotton construction may advantageously be employed where the device is to be used in a bathroom, the rug being subject to moisture and requiring frequent cleaning.

Also it is within the scope of this invention to so construct the various elements that they may be separated either for storage or for cleaning. This may be accomplished by securing the fabric to the rubber base only at preselected points with the heating element secured only to the base structure, for example.

Without further elaboration, the foregoing will so fully explain the character of my invention that others may, by applying current knowledge, readily adapt the same for use under varying conditions of service, while retaining certain features which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following claims.

I claim:

l. A floor covering comprising a planar pile surface portion, a fabric backing supporting said pile surface portion, a resilient base element secured to said fabric backing, a heating element disposed within said iloor covering, said heating element comprising two elongated electrical resistance elements following side by side tortuous paths whereby the area of said planar surface is subdivided into a plurality of small uniform areas, exible conductor means extending from each of said resistance elements, and switch means terminating said flexible conductors, said switch means comprising a housing, a plurality of wall socket engaging prongs extending from said housing, and a movable switch element mounted in said housing to selectively connect one of said resistance elements to said prongs, both of said elements to said prongs in series, or both of said resistance elements in parallel relationship.

2. A iloor covering comprising a planar pile surface portion, a fabric backing supporting said pile surface portion, a resilient base element secured to said fabric backing, a heating element disposed within said oor covering, said heating element comprising two elongated electrical resistance elements following side-by-side tortuous paths whereby the area of said planar surface is subdivided into a plurality of small substantially uniform areas, exible conductor means extending from each of said resistance elements, and switch means terminating said flexible conductor means comprising a housing, a plurality of wall socket engaging prongs extending from said housing, and a movable switch 'element mounted in said housing to selectively connect each one of said resistance elements to said prongs.

References Cited in the iile of this patent UNITED STATES PATENTS 1,004,270 Shaler Nov. 12, 1912 1,921,343 Burkholder Aug. 8, 1933 2,025,586 Hall Dec. 24, 1935 2,107,598 Colvin Feb. 8, 1938 2,511,540 Osterheld lune 13, 1950 2,619,580 Pontiere Nov. 25, 1952 2,712,592 Goldstein et al. July 5, 1955 

